U.S. patent application number 11/343163 was filed with the patent office on 2007-08-02 for positive lubrication of a meshing gear.
This patent application is currently assigned to Honeywell International, Inc.. Invention is credited to Walter L. Meacham, Mark A. Shilo, John T. Zadik.
Application Number | 20070175706 11/343163 |
Document ID | / |
Family ID | 37908380 |
Filed Date | 2007-08-02 |
United States Patent
Application |
20070175706 |
Kind Code |
A1 |
Shilo; Mark A. ; et
al. |
August 2, 2007 |
Positive lubrication of a meshing gear
Abstract
A device and method for the lubrication of teeth in a meshing
gear. A plurality of teeth are formed about a periphery of a
toothed wheel. Each tooth is defined by a root portion, an involute
profile portion, and a minimal stress portion. The device and
method includes the formation of a plurality of fluidic passages,
each including an inlet and an outlet, in fluidic communication
with a lubricant and the minimal stress portion of at least one of
the plurality of teeth. During operation, the lubricant contained
flows via centrifugal force to the minimal stress portion of each
of the plurality of teeth via the fluidic passages. The fabrication
of the outlet of the fluidic passages at a minimal stress portion
of at least one of the plurality of teeth eliminates any further
stress fabrication on the portion of the tooth structure that is
under stress during operation.
Inventors: |
Shilo; Mark A.; (Scottsdale,
AZ) ; Meacham; Walter L.; (Phoenix, AZ) ;
Zadik; John T.; (Tempe, AZ) |
Correspondence
Address: |
HONEYWELL INTERNATIONAL INC.
101 COLUMBIA ROAD
P O BOX 2245
MORRISTOWN
NJ
07962-2245
US
|
Assignee: |
Honeywell International,
Inc.
|
Family ID: |
37908380 |
Appl. No.: |
11/343163 |
Filed: |
January 30, 2006 |
Current U.S.
Class: |
184/6.12 ;
184/6.13 |
Current CPC
Class: |
F16H 57/0427 20130101;
F16H 57/0493 20130101; F16H 57/0431 20130101 |
Class at
Publication: |
184/006.12 ;
184/006.13 |
International
Class: |
F16H 57/04 20060101
F16H057/04; F01M 1/12 20060101 F01M001/12 |
Claims
1. A gear assembly, comprising: a shaft configured to rotate; a
toothed wheel mounted on the shaft and configured to rotate
therewith, the toothed wheel having a plurality of teeth formed on,
and extending radially from, a periphery thereof, each of the
plurality of teeth defined by a root portion, an involute profile
portion, and a minimal stress portion located between the root
portion and the involute profile portion; a source of lubricant
adapted to supply a lubricant to the gear assembly; and a plurality
of fluidic passages, each fluidic passage in fluidic communication
with the source of lubricant and the minimal stress portion of one
of the plurality of teeth, whereby, during gear assembly operation,
lubricant supplied by the source of lubricant flows, under the
influence of centrifugal force, to the minimal stress portion of
each of the plurality of teeth via the plurality of fluidic
passages.
2. The device of claim 1, wherein the source of lubricant is an
external jet that provides lubricant to an ID bore of the
shaft.
3. The device of claim 1, wherein the source of lubricant is an
internal source housed in the gear assembly that provides lubricant
to an ID bore of the shaft.
4. The device of claim 1, wherein the plurality of fluidic passages
are circumferentially positioned about the shaft.
5. The device of claim 1, further including an annular well formed
in the gear assembly between the shaft and the plurality of teeth,
the annular well in fluidic communication with the source of
lubricant and adapted to receive the lubricant.
6. The device of claim 5, wherein the plurality of fluidic passages
are circumferentially positioned about the annular well.
7. The device of claim 1, wherein each of the plurality of fluidic
passages includes a fluid inlet and a fluid outlet, and wherein the
fluid inlet is in fluidic communication with the source of
lubricant and the fluid outlet is in fluidic communication with the
minimal stress portion of one of the plurality of teeth.
8. The device of claim 1, wherein each of the plurality of teeth is
in fluidic communication with a fluidic passage.
9. The device of claim 1, wherein the lubricant is a lubricating
oil.
10. A gear assembly, comprising: a shaft configured to rotate; a
toothed wheel mounted on the shaft and configured to rotate
therewith, the toothed wheel having a plurality of teeth formed on,
and extending radially from, a periphery thereof, each of the
plurality of teeth defined by a root portion, an involute profile
portion, and a minimal stress portion located between the root
portion and the involute profile portion; an annular well formed in
the gear assembly between the shaft and the plurality of teeth and
adapted to receive a lubricant; a plurality of fluidic passages,
each fluidic passage in fluidic communication with the annular well
and one of the minimal stress portion of one of the plurality of
teeth or the involute profile of one of the plurality of teeth,
whereby, during gear assembly operation, lubricant flows, under the
influence of centrifugal force, to the plurality of teeth via the
plurality of fluidic passages.
11. The device of claim 10, wherein the plurality of fluidic
passages are circumferentially positioned about the annular
well.
12. The device of claim 10, wherein each of the plurality of
fluidic passages includes a fluid inlet and a fluid outlet, wherein
each of the fluid inlets is in fluidic communication with the
annular well, and each of the fluid outlets is in fluidic
communication with the minimal stress portion of one of the
plurality of teeth.
13. The device of claim 10, wherein each of the plurality of teeth
is in fluidic communication with a fluidic passage.
14. The device of claim 10, wherein the source of lubricant is
disposed in the shaft.
15. The device of claim 10, wherein the source of lubricant is a
jet supply source.
16. The device of claim 10, wherein the lubricant is one of a
lubricating oil or grease.
17. A method of lubricating a plurality of teeth in a meshing gear
comprising the steps of: providing a shaft configured to rotate;
mounting a tooth wheel on the shaft, the toothed wheel configured
to rotate therewith, the toothed wheel having a plurality of teeth
formed on, and extending radially from, a periphery thereof, each
of the plurality of teeth defined by a root portion, an involute
profile portion, and a minimal stress portion located between the
root portion and the involute profile portion; providing a source
of lubricant adapted to supply a lubricant to the gear assembly;
and forming a plurality of fluidic passages, each fluidic passage
in fluidic communication with the source of lubricant and the
minimal stress portion of one of the plurality of teeth, whereby
during gear assembly operation, lubricant flows, under the
influence of centrifugal force, to the minimal stress portion of
each of the plurality of teeth via the plurality of fluidic
passages.
18. The method of claim 17, wherein the source of lubricant is an
external jet.
19. The method of claim 17, wherein the source of lubricant is an
internal source housed in the gear.
20. The method of claim 17, further including the step of providing
an annular well in the gear assembly between the shaft and the
plurality of teeth, the annular well in fluidic communication with
the source of lubricant and adapted to receive the lubricant.
21. The method of claim 17, wherein the step of forming a plurality
of fluidic passages includes forming a fluid inlet and a fluid
outlet, wherein each of the fluid inlets is in fluidic
communication with the lubricant, and each of the fluid outlets is
in fluidic communication with the minimal stress portion of at
least one of the plurality of teeth.
22. The method of claim 17, wherein the step of forming a plurality
of fluidic passages includes forming the fluidic passages
circumferentially positioned about the annular well.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to the lubrication of gears.
More particularly, the present invention relates to the lubrication
of toothed meshing gears.
BACKGROUND OF THE INVENTION
[0002] It is well known to dispose meshing gears in a lubricant
filled case. The lubricant, which may be either solid or liquid,
bathes the gears, creating a lubricating field that maintains gear
lubrication. Alternative means of lubricating meshing gears have
been used, such as through the use of a static oil jet mounted on
the gearbox structure that disperses lubricant onto the meshing
teeth. Oil jet dispersion typically is achieved in one of two ways:
as an into-mesh jet where oil is dispersed onto the teeth prior to
meshing, or as an out-of-mesh jet where lubricant is dispersed onto
the teeth as they complete the mesh. In addition, a cooling oil
splash or mist has been used to lubricate meshing gears in which
high speed components churn oil spray through a gearbox space.
[0003] Insufficient lubrication between meshing gears can cause
scoring, micropitting, and other forms of wear and damage to the
involute profile of the gear teeth, leading to higher vibration,
noise, heat, and ultimately gear tooth failure. Generally, in a
meshing gear that turns in a single direction, while under a loaded
condition, one side of the tooth (and one side of the tooth root)
is subject to the highest stress because the load is applied
adjacent to that point. More specifically, the highest tensile
stress on the gear tooth is located at a point in the tooth root
adjacent to where the tooth is being pushed, receiving the greatest
load during the period of revolution when there is single tooth
contact.
[0004] Various attempts have been made to provide lubricating film
on the gear teeth. These include providing a lubricant directly to
each of the centers of the roots of the gear teeth or to the
involute profile of each of the gear teeth, both highly stressed
points. In general, prior attempts have formed a fluid passage hole
located within this high stress region. This can be considered a
rotating oil jet. Lubricant is fed to the high stress points during
operation by centrifugal force. The fabrication of a passage within
the tooth in this high stress region may cause an even higher
stress concentration about the passage. This can exacerbate the
possibility of a crack developing and the gear tooth breaking off.
Attempts at providing lubrication to a lower stress point of each
of the gear teeth, or to a location that is distant from the
maximum stress point of the gear teeth, has not been achieved.
[0005] Thus, there is a need for a means for lubricating a meshed
gear assembly wherein a constant lubricating film is provided by a
rotating jet at a minimal stress point of a plurality of gear teeth
that form the meshed gears, thereby achieving a constant
lubricating film during a loaded condition.
SUMMARY OF THE INVENTION
[0006] The present invention provides a gear assembly, comprising:
a shaft, a toothed wheel, a source of lubricant and a plurality of
fluidic passages. The toothed wheel is mounted on the shaft and
configured to rotate therewith. The toothed wheel has a plurality
of teeth formed on, and extending radially from, a periphery
thereof. Each of the plurality of teeth is defined by a root
portion, an involute profile portion, and a minimal stress portion
located between the root portion and the involute profile portion.
The source of lubricant is adapted to supply a lubricant to the
gear assembly, either through a bore in the shaft or from an
external jet source. Each of the plurality of fluidic passages is
in fluidic communication with the source of lubricant and the
minimal stress portion of one of the plurality of teeth. During
gear assembly operation, lubricant flows, under the influence of
centrifugal force, to the minimal stress portion of each of the
plurality of teeth via the plurality of fluidic passages.
[0007] In another exemplary embodiment, provided is a gear
assembly, comprising, a shaft, a toothed wheel, an annular well,
and a plurality of fluidic passages. The toothed wheel is mounted
on the shaft, and configured to rotate therewith. The toothed wheel
includes a plurality of teeth formed on, and extending radially
from, a periphery thereof. Each of the plurality of teeth is
defined by a root portion, an involute profile portion, and a
minimal stress portion located between the root portion and the
involute profile portion. The annular well is formed in the gear
assembly between the shaft and the plurality of teeth and adapted
to receive a lubricant. Each of the plurality of fluidic passages
is in fluidic communication with the annular well and the minimal
stress portion of one of the plurality of teeth. During operation,
lubricant flows, under the influence of centrifugal force, to the
plurality of teeth via the fluidic passages.
[0008] In addition, provided is a method of lubricating a plurality
of teeth in a meshing gear comprising the steps of providing a
shaft, configured to rotate, and a toothed wheel mounted on the
shaft. The toothed wheel also configured to rotate. The method
further includes the steps of providing a source of lubricant to
provide lubricant to the gear assembly, and forming a plurality of
fluidic passages, each fluidic passage in fluidic communication
with the lubricant and the minimal stress portion of one of the
plurality of teeth. The toothed wheel is configured to rotate
therewith the shaft and includes a plurality of teeth formed on,
and extending radially from, a periphery thereof. Each of the
plurality of teeth is defined by a root portion, an involute
profile portion, and a minimal stress portion located between the
root portion and the involute profile portion. During gear assembly
operation, lubricant flows, under the influence of centrifugal
force, to the minimal stress portion of each of the plurality of
teeth via the plurality of fluidic passages.
[0009] Other independent features and advantages of the preferred
positive gear lubricating assembly will become apparent from the
following detailed description, taken in conjunction with the
accompanying drawings which illustrate, by way of example, the
principles of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a schematic representation of a cross-section of a
meshing gear taken along line 1-1 of FIG. 2 according to the
present invention;
[0011] FIG. 2 is a schematic representation of a cross-section of
the meshing gear of FIG. 1 taken along line 2-2 of FIG. 1,
according to the present invention;
[0012] FIG. 3 is a schematic representation of a cross-section of
an alternate embodiment of a meshing gear taken along line 3-3 of
FIG. 4, according to the present invention;
[0013] FIG. 4 is a schematic representation of a cross-section of
the embodiment of FIG. 3 taken along line 4-4 of FIG. 3, according
to the present invention;
[0014] FIG. 5 is a schematic representation of a cross-section of
another alternate embodiment illustrating a modification to the
embodiment shown in FIGS. 3 and 4, according to the present
invention;
[0015] FIG. 6 is a schematic representation of a cross-section of
another alternate embodiment illustrating a modification to the
embodiment shown in FIGS. 3 and 4, according to the present
invention;
[0016] FIG. 7 is a schematic representation of a cross-section of
yet another alternate embodiment illustrating a modification to the
meshing gear of FIGS. 3 and 4 taken along line 7-7 FIG. 8,
according to the present invention; and
[0017] FIG. 8 is a schematic representation of a cross-section of
the embodiment of FIG. 7 taken along line 8-8 of FIG. 7, according
to the present invention.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
[0018] The present invention employs a means for applying a
lubricant to the involute profile of a tooth on a meshing gear via
a point of low stress in the tooth root of the gear. The device and
method provide for the positive lubrication and maintenance of a
lubricating film in meshing gears. Referring now to FIGS. 1 and 2
illustrated is a portion of a gear 100, and more particularly a
toothed wheel 102, mounted on a shaft 104, sometimes referred to as
a gear assembly. The assembly may be one single piece of hardware,
but is hereinafter referred to as an assembly. The shaft 104 is
configured, upon receipt of a suitable drive force, to rotate. The
shaft 104 may simply be a bore of the gear assembly. Furthermore,
The drive force may be applied either to the shaft 104, which in
turn causes the toothed wheel 102 to rotate, or it may be applied
to the toothed wheel 102, which causes the shaft 104 to rotate.
Toothed wheel 102 includes a plurality of meshing teeth 103 each
comprised of a root portion 106 and an involute profile portion
108. Each tooth 103 has a load side 114 which is the side that
applies or receives load from the mating gear, and a coast side 116
which is not loaded. A minimal stress portion 110 is located in the
region near where the root portion 106 meets the involute profile
portion 108 on the coast side 116. This minimal stress portion 110
is the point at which relatively low tensile stress is exhibited
upon each of the meshing teeth 103.
[0019] In the embodiments described, gear 100 is a one-way gear in
which operational movement is counterclockwise as indicated by
arrows 112 (FIG. 2). It should be understood that this particular
type of counterclockwise gear movement is merely exemplary and that
a gear that operates using one-way clockwise movement may also be
used. During counterclockwise gear movement, each individual tooth
101 of the plurality of meshing teeth 103 may be subject to a
pushing load on the load side 114 of tooth 101, and is considered
to be absent a load on the coast side 116 of tooth 101.
[0020] During movement of gear 100, the load side 114 is under a
pushing force at a point where the tooth 101 is being pushed by its
meshing tooth (not shown). The highest tensile stress is exhibited
on the tooth 101 typically exhibited at the root-end of the
involute profile 108. The coast side 116 of the tooth 101 is not
under a load when gear 100 is operational.
[0021] During operation of gear 100 under some loading conditions,
loss of gear tooth contact between the plurality of teeth 103 and
their meshing teeth may occur. Variations in teeth profile or
dynamic motions may also cause a loss of gear tooth contact. During
operation of gear 100, it is desirable to maintain a lubricating
film on each tooth 101 of the plurality of teeth 103 to reduce
scoring, micropitting, and other forms of wear and damage to the
involute profile of the gear teeth.
[0022] In the embodiment disclosed in FIGS. 1 and 2, a lubricant
119, such as a lubricating oil, grease, or the like, is present
within an ID bore 105 of shaft 104 In a preferred embodiment the
lubricant is substantially fluidic to allow for flow as described
below. Lubricant 119 is deposited by either an external jet from
outside the gear, or from elsewhere in the shaft 104 or gear bore,
not shown. Gear 100 further includes a plurality of fluid passages
120 formed in, and circumferentially spaced about, shaft 104. Each
passage 120 extends from the ID bore 105 of shaft 104 to the
minimal stress portion 110 of each tooth 101. Fluid passages 120
allow the lubricant 119 to be applied to the minimal stress portion
110 of each tooth 101. As previously stated, minimal stress portion
110 of each tooth 101 is the area of the tooth 101 that has the
lowest load stress. Accordingly, the passages 120 do not place
further stress upon each individual tooth 101 at the load side
involute profile 108, where the highest tensile stress effects are
located. The lubricant 119 is retained axially within the bore 105
of shaft 104 by a feature 130, such as a pressed in annular plug, a
circular snap ring, or other design feature.
[0023] During operation, the lubricant 119 flows by centrifugal
force from the bore 105 of shaft 104 through the plurality of
passages 120 to the minimal stress portion 110 of each of the
plurality of teeth 103. Each fluid passage 120 includes an inlet
opening 122 proximate the shaft 104 and an outlet opening 124
proximate the minimal stress portion 110 of each tooth 101. The
flow of the lubricant 119 through passages 120 and through outlet
openings 124 to the minimal stress portion 110 of each tooth 101
provides lubrication to the meshing teeth 103 as the wheel is
rotated. This constant, direct supply of lubrication to each
meshing tooth 101 provides for the buildup of a lubricating film
without increasing the stress to the plurality of teeth 103, and
prevents wear of the gear teeth.
[0024] FIGS. 3 and 4 illustrate modifications to the embodiment of
FIGS. 1 and 2. Accordingly, all components of FIGS. 3 and 4 that
are similar to the components illustrated in FIGS. 1 and 2, are
designated with similar numbers, having a prime added to indicate
the different embodiment. As illustrated in FIGS. 3 and 4, gear
100' additionally includes an annular well 118 having contained
therein a lubricant 119'. Gear 100' further includes a plurality of
fluid passages 120' formed in, and circumferentially spaced about,
shaft or gear bore 104'. Each passage 120 extends from the annular
well 118 to the minimal stress portion 110' of each tooth 101'.
Fluid passages 120' allow the lubricant 119' to be applied to the
minimal stress portion 110' of each tooth 101'. As previously
stated, the passages 120' do not place further stress upon each
individual tooth 101' at the load side 114' involute profile 108',
where the highest tensile stress effects are located.
[0025] Annular well 118 is in fluidic communication with the
minimal stress portion 110' of each tooth 101' via passages 120'.
The plurality of passages 120' may be formed extending from annular
well 118 to each individual tooth 101'. In an alternative
embodiment, the plurality of passages 120' may be formed to extend
from the annular well 118 to substantially all of the individual
teeth 101', but not each individual tooth 101 '. In either case,
annular well 118 is continuously fed the lubricant 119' by
centrifugal force draining, as indicated by arrow 131, the shaft
104'. As mentioned previously, lubricant 119' is present within the
ID bore 105 of shaft 104', deposited there either by external jet
from outside the gear, or from elsewhere in the shaft or gear bore,
not shown.
[0026] During operation, the lubricant 119' flows by centrifugal
force from the annular well 118 through the plurality of passages
120' to the minimal stress portion 110' of each of the plurality of
teeth 103'. Each fluid passage 120' includes an inlet opening 122'
proximate the annular well 118 and an outlet opening 124' proximate
the minimal stress portion 110' of each tooth 101'. The flow of the
lubricant 119 through passages 120 and through outlet openings 124
to the minimal stress portion 110' of each tooth 101' provides
lubrication to the meshing teeth 103' as the wheel is rotated.
Similar to the previously described embodiment, this constant,
direct supply of lubrication to each meshing tooth 101' provides
for the buildup of a lubricating film without increasing the stress
to the plurality of teeth 103, and prevents wear of the gear
teeth.
[0027] FIG. 5 illustrates a variation on this embodiment where the
annular well 118 is continuously fed via a lubricating jet (not
shown) located in the housing static structure. The lubricating jet
supplies the lubricant 119' directly into the annular well 118.
[0028] FIG. 6 illustrates a variation on this embodiment where the
annular well 118 is continuously fed via a plurality of fluid
passages 126 which drain lubricant 119' from within the bore 105'
of shaft 104'. As in the first embodiment, the lubricant 119' is
retained axially within the bore 105' of shaft 104' by a feature
130', such as a pressed in annular plug, a circular snap ring, or
other design feature.
[0029] FIGS. 7 and 8 illustrate yet another alternate modification
of the previous embodiment wherein the plurality of passages 120'
connect the annular well 118 to the outlet opening 124' outboard of
the loaded tooth roots. The lubricant 119' is applied directly onto
the involute profiles 108' and also onto the profiles of the
meshing gear teeth (not shown) Circumferential relocation of the
passages 120' may be required to optimize the lubrication
requirements of the mating gear (not shown). Annular well is fed
via any of the methods previously discussed.
[0030] A means for lubricating a meshing gear has now been provided
that includes a plurality of lubricating passages formed
circumferentially about a shaft of a toothed wheel of a meshing
gear. The lubricating passages are in fluidic communication with a
lubricant located in the bore of the shaft or an annular well
formed about the shaft and having contained therein the lubricant.
The fluid passages are additionally in fluidic communication with a
minimal stress portion of substantially all of the teeth that
comprise the toothed wheel. The formation of the passages as this
point of minimal stress does not increase the stress upon the
plurality of teeth, yet provides a constant means for lubrication
during loaded operating conditions. The fabricating of the outlet
of the passages at a minimal stress portion of each of the
plurality of teeth minimizes the formation of additional
stress.
[0031] While the invention has been described with reference to a
preferred embodiment, it will be understood by those skilled in the
art that various changes may be made and equivalents may be
substituted for elements thereof without departing from the scope
of the invention. In addition, many modifications may be made to
adapt to a particular situation or material to the teachings of the
invention without departing from the essential scope thereof.
Therefore, it is intended that the invention not be limited to the
particular embodiment disclosed as the best mode contemplated for
carrying out this invention, but that the invention will include
all embodiments falling within the scope of the appended
claims.
* * * * *